RT Journal Article
SR Electronic
T1 Noninvasive Imaging of Islet Transplants with <sup>111</sup>In-Exendin-3 SPECT/CT
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 799
OP 804
DO 10.2967/jnumed.115.166330
VO 57
IS 5
A1 van der Kroon, Inge
A1 Andralojc, Karolina
A1 Willekens, Stefanie M.A.
A1 Bos, Desirée
A1 Joosten, Lieke
A1 Boerman, Otto C.
A1 Brom, Maarten
A1 Gotthardt, Martin
YR 2016
UL http://jnm.snmjournals.org/content/57/5/799.abstract
AB Islet transplantation is a promising treatment for type 1 diabetic patients. However, there is acute as well as chronic loss of islets after transplantation. A noninvasive imaging method that could monitor islet mass might help to improve transplantation outcomes. In this study, islets were visualized after transplantation in a rat model with a dedicated small-animal SPECT scanner by targeting the glucagonlike peptide-1 receptor (GLP-1R), specifically expressed on β-cells, with 111In-labeled exendin-3. Methods: Targeting of 111In-exendin-3 to GLP-1R was tested in vitro on isolated islets of WAG/Rij rats. For in vivo evaluation, 400 or 800 islets were transplanted into the calf muscle of WAG/Rij rats (6–8 wk old). Four weeks after transplantation, SPECT/CT images were acquired 1 h after injection of 111In-labeled exendin-3. After SPECT acquisition, the muscles containing the transplant were analyzed immunohistochemically and autoradiographically. Results: The binding assay, performed on isolated islets, showed a linear correlation between the number of islets and 111In-exendin-3 accumulation (Pearson r = 0.98). In vivo, a 1.70 ± 0.44-fold difference in tracer uptake between 400 and 800 transplanted islets was observed. Ex vivo analysis of the islet transplant showed colocalization of tracer accumulation on autoradiography, with insulin-positive cells and GLP-1R expression on immunohistochemistry. Conclusion: 111In-exendin-3 accumulates specifically in the β-cells after islet transplantation and is a promising tracer for noninvasive monitoring of the islet mass.